Answer:
If plants infested with aphids are sprayed with diluted coffee then the aphids will die.
Step-by-step explanation:
"Aphids sprayed with diluted coffee will not infest the plants" doesn't explain what happens to the aphids. (For example: they die, etc.)
"Plant sprayed with diluted coffee will not be infested by aphids" doesn't explain why it will not be infested by aphids.
"If plants with bug infestations are sprayed with diluted coffee then the bugs will die" doesn't say what type of bug, not all bugs will die from diluted coffee on plants.